Mechanisms in mineral oil or pristane induced peritoneal plasmacytomagenesis in the BALB/c mouse are investigated. The role of the granuloma in promoting neoplastic development via adherent cell: tumor cell interaction is being further studied in vitro and in vivo. The possibility of finding a similar dependence in human myeloma will also be explored. A search for the genetic basis of susceptibility continues. The role of type C RNA viruses (e.g. Abelson virus) and endogeneous type C viruses is also pursued. Antigen binding activities of myeloma proteins are determined. Groups of myeloma proteins with similar hapten binding activity are collected, and compared structurally and antigenically with antibodies of similar specificity. The BALB/c mouse has over 28 V-kappa isotypes. Specific antisera are being made to as many of these as possible for purposes of quantitating Ig-gene expression in immune responses and at the B cell level. Genetic markers controlling IgVH structure and regulation are sought and characterized. BIBLIOGRAPHIC REFERENCES: Potter, M., Rudikoff, S., Vrana, M., Rao, D. N. and Mushinski, E. B.: Primary structural differences in myeloma proteins that bind the same haptens. Cold Spring Harbor Symp. Quant. Biol. 41: 661-666, 1977. Vrana, M., Rudikoff, S. and Potter, M.: Heavy chain variable region sequence from an inulin binding myeloma protein. Biochemistry 16: 1170-1175, 1977.